Motor compressor unit with reduced noise transmission



Dec. 4, 1962 G. s. M CLOY 3,066,857

MOTOR COMPRESSOR UNIT WITH REDUCED NOISE TRANSMISSION Filed May 18, 1960EvAPoRA TOR INVENTOR BAHAM LO WITNESSES G S cc Y ATTORN Y United StatesPatent Ofifice 3,llfi6,857 Patented Dec. 4, 1962 MOTOR COMPRESSOR UNITWITH REDUCED NGISE TRANSMISSION Graham S. McCloy, Columbus, Ohio,assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Filed May 18, 1960, Ser. No. 29,869 3Claims. (Cl. 230-232) This invention relates to refrigeration apparatusand more particularly to the compressors in refrigeration units.

In constructing a refrigeration unit is is desirable to provide meansfor minimizing compressor operating noise attributable to compressorvibrations being conducted through a body of lubricating oil to theshell or case which encloses the compressor. In this type of compressorthe oil body acts as a sound transmitting medium and the case transducesthe sound wave energy into audible, disturbing noises.

In the past, various arrangements have been proposed to reduce theability of the oil body to transmit sound. For example, the copendingapplication of Richard T. Douglas, Serial No. 739,316, filed June 2,1958, now abandoned, and assigned to the assignee of the presentinvention, deals with the same problem, and solves it by conductingsuction gas through a tube into the oil body. The bubbling of gasthrough the oil body provides hundreds of air pockets thereinwhichinsulate the disturbance from the sound transducer. The presentinvention copes with the same problem but it is believed to solve itmore satisfactorily, since fewer parts are required and a more compactarrangement within the case is possible.

According to the present invention, the compressor includes a block inwhich is provided a crankcase and at least one cylinder. A piston isslidably fitted within the cylinder and is adapted to receivereciprocating forces so that it will slide back and forth therein tocompress gas on the forward stroke and to create suction on the returnstroke. The fit between the piston and the cylinder walls is such that aportion of the compressed gas will bypass the piston on the compressionstroke and enter the crankcase which, unlike conventional constructions,is closed to the crankcase except for one or more openings which extendinto the oil body. With this arrangement the gas bypassed on thecompression stroke is discharged into the oil body and it bubblestherethrough, eventually being returned to the compression chamber forrecompression. The bubbling of the bypass gas through the oil bodyaerates the oil and provides it with insulation properties, therebyreducing its ability to transmit sound. Furthermore, the oil bodyabsorbs acoustic energy and reduces reverberations. As a result thecompressor is quieter running than prior constructions.

The various objects, features and advantages of the invention willappear more fully from the following detailed description and claimstaken in connection with the accompanying drawing, forming part of thisapplication, and wherein:

The single FIGURE of the drawing is a vertical, sectional and partiallyschematic view of refrigeration apparatus embodying the invention.

The invention, as shown in the drawing, is applied to a hermetic orsealed refrigeration compressor comprising a two-part case having upperand lower pressed sheet metal sections 11 and 12, in which is disposed amain casting 14 for mounting an electric driving motor 16, and acompressor generally designated by the numeral 18. The main casting 14includes an upstanding annular flange into which is pressed the stator22 of the motor 16, and a central upright bearing boss 24. The latterreceives a drive shaft 26, to the upper end of which is secured themotor rotor 28.

The annular flange 20 and bearing boss 24 are interconnected by anannular web 30 from which depends a cylinder block 32 for the compressor18. The block 32 is formed with a radially extending cylinder 34 adaptedto receive a reciprocable piston 36. The piston 36 slides back and forthin the cylinder 34 in response to reciproeating forces received througha connecting rod 38 from a crank 40 formed on the lower end of the driveshaft 26.

The cylinder block 32 is made hollow adjacent the cylinder 34 to providethere a crankcase 42 in which the connecting rod 38 and crank 40 may beaccommodated. An opening in the lower end of the block 32 is closed by aplate 43 in which is journalled the lower end of shaft 26. In addition,an access opening in block 32 to the interior of the crankcase 42 isclosed by a cover 44.

The compressor assembly 18 is resiliently supported, to preclude noise,by means of helical compression springs 45, preferably, three, eachconnected between the annular flange 20 and an inwardly extendingsupporting member 46 carried by the lower case section 12.

Refrigerant leaves the compressor cylinder 34 through an outlet 47,passes through a mutiler 4.8, and is conducted by a discharge conduit 50to a condenser 52 outside the case 10. Condensed refrigerant is expandedthrough expansion means 54 and boiled off in an evaporator 56, afterwhich it is returned to the interior of the case 10 by a suction line58. After entering the case 10, refrigerant is returned to the cylinder34 through an inlet tube 59 after it has passed around the motor 16.

The bottom of the lower case section 12 holds a body or pool oflubricating oil in which is submerged the lower end of the cylinderblock 32 and the end plate 43. Also submerged in the oil pool 6%) is aduct 53 communicating with a network of passageways of a forced feedlubrication system which is neither shown nor described in detail, sinceit is of conventional construction and forms no significant part of thepresent invention.

Sound wave energy is transmitted partly by the oil pool 69 from thevibrating compressor 18 to the case it), and there transduced intodisturbing noises which emanate from the case 10'. it is the principalconcern of the present invention to reduce this noise.

The construction of the compressor, as thus far described, is unique forcompressors of the type which receive suction gas directly into the casefor use in cooling the motor on its way to the compressor chamber.Ordinarily, in this type of compressor, the crankcase 42 is open to theinterior of the case 10 simply to reduce the weight of the cylinderblock 32, and because no use has been made heretofore of gas blown bythe piston 36 during the compression stroke. The present arrangementcloses the access opening to the crankcase 42 by the cover 44 andprovides, in addition, one or more opening-s or passageways 64 throughplate 43 at the lower end of the cylinder block 32. Openings 64therefore provide communication between the crankcase 42 and thatportion of the oil pool 60 directly beneath the compressor 18; and it isthrough these openings 64 that bypass gas is discharged from thecrankcase and bubbled through the oil pool to the surface thereof, wherea froth or foam is formed.

Refrigerant within the crankcase '42 is at a higher pressure than thesuction gas circulating inside the case 19 so that how from thecrankcase through the oil pool 69 to the circulating suction gas ispromoted. This provision aerates the oil pool 60 and produces a largenumber of air pockets in the oil pool which reduce its ability totransmit sound wave energy. Additionally, the oil pool 60 reducesreverberations by absorbing acoustic energy.

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Compressors constructed according to this invention have been found torun appreciably quieter than those constructed according to the priorart.

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various changes and modifications without departing fromthe spirit thereof.

What is claimed is:

1. In refrigeration apparatus, a hermetic case, a liquid body in saidcase, a compressor resiliently mounted within said case in spacedrelation thereto, said compressor having a portion submerged in saidliquid body, said compressor including a closed crankcase, at least onecylinder communicating with said crankcase, and a reciprocable pistonslidably fitted within said cylinder to provide a compression chamber,said piston compressing the gas in said chamber on moving in onedirection and providing suction in said chamber on moving in the otherdirection, means providing at least one passageway establishingcommunication between said crankcase and said liquid body adiacent thesubmerged portion of said -compressor, the lit between said piston andsaid cylinder permitting some compressed gas to bypass said piston tosaid crankcase, the gas being forced out said passageway and throughsaid liquid body during operation of said piston, whereby foaming ofsaid liquid body is eifected and the ability of said liquid body totransmit sound wave energy is reduced.

2. In refrigeration apparatus, a gas containing shell, a body of liquidin said shell, a resiliently mounted compressor disposed within saidshell in spaced relation thereto and partly submerged in said liquidbody, said compressor comprising a closed crankcase and at least onecylinder communicating with said crankcase, a piston slidably fittedwithin said cylinder and cooperating therewith to provide a compressionchamber, means for operating said piston in said cylinder in areciprocating motion to provide compression of said gas on the forwardstroke of said piston and suction on the return stroke of said piston,means for admitting gas to be compressed into said compression chamberduring said suction stroke of said piston, means for discharging saidgas outside said shell from said compression chamber during said forwardstroke of said piston, means providing at least one passageway providingcommunication between said crankcase and said liquid body, the fitbetween said piston and said cylinder permitting some compressed gas tobypass said piston to said crankcase and thence pass through saidpassageway and said liquid body during operation of said piston; thepassage of gas through said oil body reducing its ability to transmitsound wave energy.

3. In refrigeration apparatus, a gas containing shell, a compressorspaced from said shell and resiliently mounted in said shell foroperation therein, said compressor comprising in a lower portion thereofa closed crankcase and at least one cylinder which intercornmunicate, abody of oil in said shell and in which is submerged the lower portion ofsaid compressor including at least part of said crankcase, a pistonslidably fitted within said cylinder and cooperating therewith toprovide a compression chamber, means for operating said piston in saidcylinder in a reciprocating motion to provide compression of said gas onthe forward stroke of said piston and suction on the return stroke ofsaid piston, means for admitting gas to be compressed first into saidshell and then into said compression chamber during said suction strokeof said piston, means for discharging said gas outside said shell fromsaid compression chamber during said forward stroke of said piston,means providing at least one passageway for communication between saidcrankcase and said oil body, the fit between said piston and saidcylinder permitting some compressed gas to bypass said piston to saidcrankcase and thence through said passageway to said oil body duringreciprocating motion of said piston, whereby during the operation ofsaid piston the pressure in said crankcase exceeds the pressure withinsaid shell and bypassed gas is bubbled through said oil body anddischarged into said shell, the bubbling of gas through said oil bodyreducing its ability to transmit sound wave energy.

References Cited in the file of this patent UNITED STATES PATENTS1,348,828 Fessenden Aug. 3, 1920 1,897,199 Kenney Feb. 14, 19332,699,117 La Prairie Jan. 11, 1955 2,721,029 Grimshaw Oct. 18, 19552,764,342 Dills Sept. 25, 1956

